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Abstract:

The present disclosure relates to a method for controlling a wind
turbine, the wind turbine including at least one movable portion which is
movable during operation of the wind turbine and at least one movable
portion device including at least one of a movable portion transmitter or
a movable portion receiver, the movable portion transmitter or the
movable portion receiver being disposed at the least one movable portion;
the method including: at least one of sending to or receiving from at
least three reference points at least one signal by at least one of the
movable portion transmitter or movable portion receiver; and determining
at least one operational parameter of the wind turbine depending on at
least one characteristic of the at least one received signal. Further the
present disclosure relates to a wind turbine arrangement and a system for
controlling a wind turbine, comprising a controller of the wind turbine
and a movable portion.

Claims:

1. A method for controlling a wind turbine, wherein the wind turbine
comprises at least one movable portion which is movable during operation
of the wind turbine and at least one movable portion device including at
least one of a movable portion transmitter or a movable portion receiver,
the movable portion transmitter or the movable portion receiver being
disposed at the least one movable portion, wherein the method comprises:
at least one of sending to or receiving from at least three reference
points at least one signal by at least one of the movable portion
transmitter or movable portion receiver; and, determining at least one
operational parameter of the wind turbine depending on at least one
characteristic of the at least one received signal.

2. The method according to claim 1, further comprising: determining a
position of the at least one movable portion depending on the at least
one characteristic of the at least one signal; and, determining the at
least one operational parameter depending on the position of the at least
one movable portion.

3. The method according to claim 2, further comprising: providing or
sending the at least one position of the at least one movable portion or
the operational parameter to a control device of the wind turbine.

4. The method according to claim 3, wherein the position is determined
and sent by the movable portion device.

5. The method according to claim 1, wherein at least three of the at
least three reference points are selected from a group consisting of:
satellites of a global navigation satellite system, and earth-connected
reference points being fixed to the earth.

6. The method according to claim 1, wherein at least one of the at least
three reference points is located in at least one of the wind turbine or
another wind turbine.

7. The method according to claim 1, wherein the at least one
characteristic is at least one of the following: a respective running
time between the movable portion receiver or transmitter and the at least
three reference points; a round trip time between the movable portion
receiver or transmitter and the at least three reference points; at least
two signal angles between signals between the movable portion receiver or
transmitter and the at least three reference points; and, a time of
arrival of the at least one signal between the movable portion receiver
or transmitter and the at least three reference points.

8. The method according to claim 7, wherein the at least one signal for
determining the at least one characteristic is received by at least one
of the movable portion receiver or a receiver at at least one of the at
least three reference points.

9. The method according to claim 1, wherein the operational parameter is
determined by using at least one of triangulation, multilateration, or
trilateration using the at least one characteristic of the at least one
signal.

10. The method according to claim 1, wherein the signal is at least one
of the following: an electromagnetic signal, and an ultrasonic signal.

11. The method according to claim 1, wherein the movable portion device
is a RFID tag.

12. The method according to claim 1, wherein the at least one operational
parameter is at least one of the following: a rotational speed of a wind
rotor, a rotational speed of a generator rotor, a bending of the rotor
shaft, a bending of a tower of the wind turbine, the bending of a rotor
blade, an azimuth position, and a pitch of a rotor blade.

13. The method according to claim 1, wherein the at least one movable
portion is at least one of the following: a rotor blade tip, a portion of
a rotor shaft, a portion of a tower of the wind turbine, a portion of a
nacelle of the wind turbine, a portion of a hub of the wind turbine, and
a base of the tower of the wind turbine.

14. The method according to claim 1, further comprising operating the
wind turbine depending on the at least one operational parameter.

15. A wind turbine arrangement, comprising: (a) at least one wind turbine
including a movable portion that is movable during operation of the wind
turbine; (b) at least one movable portion device including a movable
portion transmitter or movable portion receiver adapted to at least one
of sending or receiving from to at least three reference points at least
one signal, wherein the movable portion transmitter or movable portion
receiver is arranged at the movable portion; and, (c) at least one first
controller adapted to determine an operational parameter of the wind
turbine depending on at least one characteristic of the at least one
received signal.

16. The wind turbine according to claim 15, further comprising at least
one second controller adapted to determine the position of the at least
one movable portion depending on at least one characteristic of the at
least one signal; wherein the at least one first controller is adapted to
determine at least one operational parameter of the wind turbine
depending on the position.

17. The wind turbine arrangement according to claim 16, wherein the at
least one of the at least one first controller or the at least one second
controller is respectively arranged at the movable portion.

18. The wind turbine arrangement according to claim 15, wherein the at
least one characteristic is at least one of the following: a respective
running time between the movable portion receiver or transmitter and the
at least three reference points; a round trip time between the movable
portion receiver or transmitter and the at least three reference points;
at least two signal angles between signals between the movable portion
receiver or transmitter and the at least three reference points; and, a
time of arrival of the at least one signal between the movable portion
receiver or transmitter and the at least three reference points.

19. The wind turbine arrangement according to claim 16, wherein the at
least one first control device or the at least one second control device
are integrated in the same control unit.

20. A system for controlling a wind turbine, comprising: (a) a controller
of the wind turbine; and (b) a movable portion of a wind turbine adapted
to be movable during operation of the wind turbine, wherein the movable
portion comprises at least one position determination device including a
movable portion transmitter or a movable portion receiver adapted to at
least one of sending or receiving at least one signal, wherein the
position determination device is adapted to determine a position of the
movable portion of the wind turbine depending on at least one
characteristic of the at least one signal, and is adapted to send the
position to the controller of the wind turbine.

Description:

BACKGROUND OF THE INVENTION

[0001] The subject matter described herein relates to methods and systems
for operating a wind turbine and a wind turbine arrangement, and more
particularly, to methods and systems for determining at least one
position of at least one movable portion of the wind turbine.

[0002] At least some known wind turbines include a tower and a nacelle
mounted on the tower. A rotor is rotatably mounted to the nacelle and is
coupled to a generator by a shaft. A plurality of blades extend from the
rotor. The blades are oriented such that wind passing over the blades
turns the rotor and rotates the shaft, thereby driving the generator to
generate electricity.

[0003] Operational parameters like rotor speed, rotor position, blade
bending or deflection and tower bending or deflection are used to control
a wind turbine. Usually, all of these parameters are provided by
customized sensors. Examples of sensors include: strain gauges,
incremental encoders, absolute encoders, and acceleration sensors, and
are used to measure the rotor speed, rotor position, blade bending or
deflection, tower bending or deflection, tower acceleration, main shaft
bending and blade angle. Some of these sensors are sensitive, cost
intensive or unreliable.

[0004] Many different sensors are used to provide certain operational
parameters for the wind turbine control system, for example rotational
speed, tower bending, shaft bending, and blade pitch. This increases the
costs of each single sensor, and for different sensors different failure
detection algorithms or devices may be used. Extensive engineering effort
is required to specify, design and implement these sensors. It is
desirable to provide a more reliable and cheaper method or arrangement to
determine the operational parameters of the wind turbine.

BRIEF DESCRIPTION OF THE INVENTION

[0005] In one aspect, a method for controlling a wind turbine is provided.
The wind turbine includes at least one movable portion which is movable
during operation of the wind turbine and at least one movable portion
device including at least one of a movable portion transmitter or a
movable portion receiver. The movable portion transmitter or the movable
portion receiver are disposed at the least one movable portion. The
method includes: at least one of sending to or receiving from at least
three reference points at least one signal by at least one of the movable
portion transmitter or movable portion receiver; and determining at least
one operational parameter of the wind turbine depending on at least one
characteristic of the at least one received signal.

[0006] In another aspect, a wind turbine arrangement is provided. The wind
turbine arrangement includes at least one wind turbine including a
movable portion that is movable during operation of the wind turbine; at
least one movable portion device. The at least one movable portion device
includes a movable portion transmitter or movable portion receiver
adapted to at least one of sending to or receiving from to at least three
reference points at least one signal. The movable portion transmitter or
movable portion receiver is arranged at the movable portion. At least one
first controller adapted to determine an operational parameter of the
wind turbine depending on at least one characteristic of the at least one
received signal.

[0007] In yet another aspect, a system for controlling a wind turbine is
provided. The system comprises a controller of the wind turbine and
movable portion of a wind turbine adapted to be movable during operation
of the wind turbine. The movable portion includes at least one position
determination device including a movable portion transmitter or movable
portion receiver adapted to at least one of sending or receiving at least
one signal. The position determination device is adapted to determine a
position of the movable portion of the wind turbine depending on at least
one characteristic of the at least one signal, and is adapted to send the
position to the controller of the wind turbine.

[0008] Further aspects, advantages and features of the present invention
are apparent from the dependent claims, the description and the
accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] A full and enabling disclosure, including the best mode thereof, to
one of ordinary skill in the art, is set forth more particularly in the
remainder of the specification, including reference to the accompanying
figures wherein:

[0010] FIG. 1 is a perspective view of an exemplary wind turbine.

[0011]FIG. 2 is an enlarged section view of a portion of the wind turbine
shown in FIG. 1.

[0012]FIG. 3 is a schematical view of a wind turbine arrangement
according to embodiments described.

[0014] FIG. 5 is a schematical drawing of a wind turbine arrangement
according to embodiments disclosed herein.

[0015]FIG. 6 is a schematical flow chart according to an embodiment of a
method.

DETAILED DESCRIPTION OF THE INVENTION

[0016] Reference will now be made in detail to the various embodiments,
one or more examples of which are illustrated in each figure. Each
example is provided by way of explanation and is not meant as a
limitation. For example, features illustrated or described as part of one
embodiment can be used on or in conjunction with other embodiments to
yield yet further embodiments. It is intended that the present disclosure
includes such modifications and variations.

[0017] The embodiments described herein include a wind turbine system in
which the operational parameters may be determined reliably. More
specifically, only one type of device may be used to determine the
operational parameters. Operational parameters may be parameters used to
control the operation of the wind turbine.

[0018] As used herein, the term "blade" is intended to be representative
of any device that provides a reactive force when in motion relative to a
surrounding fluid. As used herein, the term "wind turbine" is intended to
be representative of any device that generates rotational energy from
wind energy, and more specifically, converts kinetic energy of wind into
mechanical energy. As used herein, the term "wind generator" is intended
to be representative of any wind turbine that generates electrical power
from rotational energy generated from wind energy, and more specifically,
converts mechanical energy converted from kinetic energy of wind to
electrical power.

[0019] FIG. 1 is a perspective view of an exemplary wind turbine 10. In
the exemplary embodiment, wind turbine 10 is a horizontal-axis wind
turbine. Alternatively, wind turbine 10 may be a vertical-axis wind
turbine. In the exemplary embodiment, wind turbine 10 includes a tower 12
that extends from a support system 14, a nacelle 16 mounted on tower 12,
and a rotor 18 that is coupled to nacelle 16. Rotor 18 includes a
rotatable hub 20 and at least one rotor blade 22 coupled to and extending
outward from hub 20. In the exemplary embodiment, rotor 18 has three
rotor blades 22. In an alternative embodiment, rotor 18 has more or less
than three rotor blades 22. In the exemplary embodiment, tower 12 is
fabricated from tubular steel to define a cavity (not shown in FIG. 1)
between support system 14 and nacelle 16. In an alternative embodiment,
tower 12 is any suitable type of tower having any suitable height.

[0021] In one embodiment, rotor blades 22 have a length ranging from about
15 meters (m) to about 91 m. Alternatively, rotor blades 22 may have any
suitable length that enables wind turbine 10 to function as described
herein. For example, other non-limiting examples of blade lengths include
10 m or less, 20 m, 37 m, or a length that is greater than 91 m. As wind
strikes rotor blades 22 from a direction 28, rotor 18 is rotated about an
axis of rotation 30. As rotor blades 22 are rotated and subjected to
centrifugal forces, rotor blades 22 are also subjected to various forces
and moments. As such, rotor blades 22 may deflect and/or rotate from a
neutral, or non-deflected, position to a deflected position.

[0022] Moreover, a pitch angle or blade pitch of rotor blades 22, i.e., an
angle that determines a perspective of rotor blades 22 with respect to
direction 28 of the wind, may be changed by a pitch adjustment system 32
to control the load and power generated by wind turbine 10 by adjusting
an angular position of at least one rotor blade 22 relative to wind
vectors. Pitch axes 34 for rotor blades 22 are shown. During operation of
wind turbine 10, pitch adjustment system 32 may change a blade pitch of
rotor blades 22 such that rotor blades 22 are moved to a feathered
position, such that the perspective of at least one rotor blade 22
relative to wind vectors provides a minimal surface area of rotor blade
22 to be oriented towards the wind vectors, which facilitates reducing a
rotational speed of rotor 18 and/or facilitates a stall of rotor 18.

[0023] In the exemplary embodiment, a blade pitch of each rotor blade 22
is controlled individually by a control system 36. Alternatively, the
blade pitch for all rotor blades 22 may be controlled simultaneously by
control system 36. Further, in the exemplary embodiment, as direction 28
changes, a yaw direction of nacelle 16 may be controlled about a yaw axis
38 to position rotor blades 22 with respect to direction 28.

[0024] In the exemplary embodiment, control system 36 is shown as being
centralized within nacelle 16, however, control system 36 may be a
distributed system throughout wind turbine 10, on support system 14,
within a wind farm, and/or at a remote control center. Control system 36
includes a processor 40 configured to perform the methods and/or steps
described herein. Further, many of the other components described herein
include a processor. As used herein, the term "processor" is not limited
to integrated circuits referred to in the art as a computer, but broadly
refers to a controller, a microcontroller, a microcomputer, a
programmable logic controller (PLC), an application specific integrated
circuit, and other programmable circuits, and these terms are used
interchangeably herein. It should be understood that a processor and/or a
control system can also include memory, input channels, and/or output
channels.

[0025] In the embodiments described herein, memory may include, without
limitation, a computer-readable medium, such as a random-access memory
(RAM), and/or a computer-readable non-volatile medium, such as flash
memory. Alternatively, a floppy disk, a compact-disc read-only memory
(CD-ROM), a magneto-optical disk (MOD), and/or a digital versatile disc
(DVD) may also be used. Also, in the embodiments described herein, input
channels include, without limitation, sensors and/or computer peripherals
associated with an operator interface, such as a mouse and a keyboard.
Further, in the exemplary embodiment, output channels may include,
without limitation, a control device, an operator interface monitor
and/or a display.

[0026] Processors described herein process information transmitted from a
plurality of electrical and electronic devices that may include, without
limitation, sensors, actuators, compressors, control systems, and/or
monitoring devices. Such processors may be physically located in, for
example, a control system, a sensor, a monitoring device, a desktop
computer, a laptop computer, a programmable logic controller (PLC)
cabinet, and/or a distributed control system (DCS) cabinet. RAM and
storage devices store and transfer information and instructions to be
executed by the processor(s). RAM and storage devices can also be used to
store and provide temporary variables, static (i.e., non-changing)
information and instructions, or other intermediate information to the
processors during execution of instructions by the processor(s).
Instructions that are executed may include, without limitation, wind
turbine control system control commands. The execution of sequences of
instructions is not limited to any specific combination of hardware
circuitry and software instructions.

[0027]FIG. 2 is an enlarged sectional view of a portion of wind turbine
10. In the exemplary embodiment, wind turbine 10 includes nacelle 16 and
hub 20 that is rotatably coupled to nacelle 16. More specifically, hub 20
is rotatably coupled to an electric generator 42 positioned within
nacelle 16 by rotor shaft 44 (sometimes referred to as either a main
shaft or a low-speed shaft), a gearbox 46, a high-speed shaft 48, and a
coupling 50. In the exemplary embodiment, rotor shaft 44 is disposed
coaxial to longitudinal axis 66. Rotation of rotor shaft 44 rotatably
drives gearbox 46 that subsequently drives high-speed shaft 48.
High-speed shaft 48 rotatably drives generator 42 with coupling 50 and
rotation of high-speed shaft 48 facilitates production of electrical
power by generator 42. Gearbox 46 and generator 42 are supported by a
support 52 and a support 54. In the exemplary embodiment, gearbox 46
utilizes a dual path geometry to drive high speed shaft 48.
Alternatively, rotor shaft 44 is coupled directly to generator 42 with
coupling 50.

[0028] Nacelle 16 also includes a yaw drive mechanism 56 that may be used
to rotate nacelle 16 and hub 20 on yaw axis 38 (shown in FIG. 1) to
control the perspective of rotor blades 22 with respect to direction 28
of the wind. Nacelle 16 also includes at least one meteorological mast 58
that includes a wind vane and anemometer (neither shown in FIG. 2). Mast
58 provides information to control system 36 that may include wind
direction and/or wind speed. In the exemplary embodiment, nacelle 16 also
includes a main forward support bearing 60 and a main aft support bearing
62.

[0029] Forward support bearing 60 and aft support bearing 62 facilitate
radial support and alignment of rotor shaft 44. Forward support bearing
60 is coupled to rotor shaft 44 near hub 20. Aft support bearing 62 is
positioned on rotor shaft 44 near gearbox 46 and/or generator 42.
Alternatively, nacelle 16 includes any number of support bearings that
enable wind turbine 10 to function as disclosed herein. Rotor shaft 44,
generator 42, gearbox 46, high speed shaft 48, coupling 50, and any
associated fastening, support, and/or securing device including, but not
limited to, support 52 and/or support 54, and forward support bearing 60
and aft support bearing 62, are sometimes referred to as a drive train
64.

[0030]FIG. 3 shows schematically an embodiment of an arrangement for
determining operational parameters of the wind turbine. The arrangement
includes the wind turbine 10 having the wind rotor 18. The wind rotor
includes the hub 20, three rotor blades 22. In other embodiments, the
wind rotor may also include more or less rotor blades 22. Each blade has
a blade tip 68. A position determination device 70 is arranged in each
blade tip 68. Further, a position determination device 70 may be disposed
in the hub, on or in the rotor shaft 44, on the high speed shaft 48, in
the nacelle 16, and/or at a top end 72 of the tower. In FIG. 4 the
position determination device is shown in more detail. The position
determination device includes a controller 74 for determining the
position and a transceiver 76 for receiving and sending electromagnetic
signals. In other embodiments, the position determination device may
include a separate receiver and transmitter or may include only a
receiver. The signals may be transmitted via a wire connection to a wind
turbine controller 78. Similar to the control system 36 described above,
the controller 78 may also be a distributed system or arranged outside
the wind turbine 10.

[0031] In an embodiment, which may be combined with other embodiments
disclosed herein, the transceiver 76 is adapted for receiving
electromagnetic signals from satellites 80 of a global navigation
satellite system. For example, the global navigation satellite system may
be GPS (Global Positioning System), GLONASS (Russian global navigation
system), GALILEO (planned European global navigation system). Each
satellite 80 sends an electromagnetic satellite signal 82 that is
received by the transceiver 76 and the position determination device 70
may calculate its position by trilateration, using the running time or
time of flight between the satellites 80 and the transceiver 76. As only
the position of the transceiver 76 or receiver is relevant for the
calculation of the position, the controller 74 may placed away from the
transceiver 76.

[0032] The position may be sent via an electromagnetic signal 84 to the
wind turbine controller 78. For example, the wind turbine controller 78
may be located in the tower of the wind turbine. In other embodiments,
the wind turbine controller 78 may be located outside the tower of the
wind turbine. The wind turbine controller 78 may, for example, using the
position and/or the change of the position during time calculate
operational parameters of the wind turbine which may be used for
operating the wind turbine, for example a rotation of the wind rotor, an
azimuth angle of the wind rotor, a pitch of the rotor blade, a bending of
the rotor blade, a bending of the rotor shaft, and/or a bending of the
tower. The position may also be calculated in the wind turbine controller
78. Then, the position determination device 70 forwards the information
or characteristics of the electromagnetic satellite signal 82 that may be
used for the calculation of the position of the transceiver 76, and thus
the blade tip 68.

[0033] The wind turbine arrangement may include a reference station 86,
which has a known fixed position on the earth and also includes a
transceiver 88 and a controller connected to the transceiver. The
reference station is adapted for receiving electromagnetic satellite
signals 82 from the satellites 80 of the global navigation satellite
system. The reference station 86 calculates the difference between its
known position and the position calculated based on the electromagnetic
satellite signals 82 and sends this difference, or a correction signal 90
containing information how to correct the position, to the position
determination devices 70. In embodiments, which may be combined with
other embodiments disclosed herein, the correction signal may also be
sent to the wind turbine controller 78. With the information of the
correction signal 90, the position determination device or the wind
turbine controller may increase accuracy of the position of the
transceiver 76 of the position determination devices 70. For example, the
wind turbine arrangement may use a DGPS (Differential Global Positioning
System). In some embodiments, which may be combined with other
embodiments disclosed herein, the reference station may be located in the
base of the tower of the wind turbine or of a wind turbine of a wind
farm.

[0034] A local-area DGPS may be used, which may provide a millimetre level
resolution with measurements that are ambiguous to about 19 cm. More than
one, for example two or more, base stations or reference stations may be
used. At least two, for example three or more, wind turbines in a wind
farm may include a sender for a differential signal.

[0035] Depending on the terrain and the communication system, a manual
site calibration or an automated calibration may be applied to determine
the position and height of each receiver installed in a tower base.

[0036] In some embodiments, which may be combined with other embodiments
disclosed herein, the position determination devices 70 may use the
running time of electromagnetic signals from mobile phone networks to
calculate a distance to known positions of base stations of the mobile
phone network to the transceiver 76. With a trilateration the position of
the transceiver of the position determination devices 70 may be then
determined and sent to the controller 78 of the wind turbine 10.

[0037] The transceiver 76 of the position determination devices 70 may be
disposed in a movable portion of the wind turbine that is movable during
operation of the wind turbine 10, for example the top 72 of the tower 12
or the rotor blade tips 68. The controller 74 of the position
determination device 70, wherein the controller 74 is adapted to
calculate the position of the portion of the wind turbine, may be placed
away from the portion of the wind turbine, for example, in the controller
or close to the wind turbine controller 78 of the wind turbine.

[0038] FIG. 5 shows an embodiment of an arrangement for determining the
position of movable portions of a wind turbine 10. For the sake of
simplicity, the same reference numbers as in the previous drawings are
used. However, some features provided for determining the position may
have different functions compared to the embodiments described above. The
arrangement may be integrated in a wind farm. The wind farm 92 includes a
plurality of wind turbines 10, each having a tower 12 and a wind rotor
18. The wind rotor 18 has a hub 20 and rotor blades 22. Each wind turbine
10 includes movable portions, for example the hub 20, the blade tip 68,
the nacelle and/or the top end 72 of the tower 12. The actual position of
the movable portions may be used to control the wind turbines.

[0039] A position determination device 70 is arranged at the blade tips
220, the hub 20 and the tower top 72. In an embodiment, a RFID (Radio
Frequency Identification) tag may be used as a position determination
device. The position determination devices 70 include a transceiver 76
for receiving electromagnetic signals. Further, each tower base 94
includes a transmitter 96 for sending electromagnetic signals 98 to the
position determination devices 70. Based on the running time, time of
flight or reception time of the electromagnetic signal between the
transmitter 96 in the tower base 94 and the transceiver of the
positioning determination devices 70, the distance between the
transmitter 96 and the transceiver of the position determination device
70 may be determined. With at least three transmitters 96 and using
trilateration, the exact position of the transceivers 76 of the position
determination devices 70 may be determined by the position determination
devices. The determined position and/or the running time may be sent to a
controller 78 of the wind turbine, such that the wind turbine may be
controlled based on the position of the portions of the wind turbine.

[0040] In embodiments, which may be combined with other embodiments
disclosed herein, position determination devices may be located in the
tower base and the transmitters may be located in the movable portions of
the wind turbine. A round-trip time may be used to determine the position
of the movable portions of the wind turbine. For example a signal is sent
by a transceiver in the tower base, received by a transceiver in the
movable portion of the wind turbine, for example an RFID tag in a movable
portion of the wind turbine, and a return electromagnetic signal is
immediately resent back by the transceiver in the movable portion to the
transceiver. The distance may be calculated from the time between sending
of the electromagnetic signal of the transceiver in the tower base and
receiving the return electromagnetic signal. With RFID, depending on the
frequency range, a resolution of less than 1 cm is possible. In some
embodiments, the RFID tag may be located in the tower base 94, and the
movable portions may include a transmitter/receiver for energizing the
RFID chip.

[0041] In the exemplary embodiment, wind turbine controller for
controlling the wind turbine may be a real-time controller that includes
any suitable processor-based or microprocessor-based system, such as a
computer system, that includes microcontrollers, reduced instruction set
circuits (RISC), application-specific integrated circuits (ASICs), logic
circuits, and/or any other circuit or processor that is capable of
executing the functions described herein. In one embodiment, controller
78 may be a microprocessor that includes read-only memory (ROM) and/or
random access memory (RAM), such as, for example, a 32 bit microcomputer
with 2 Mbit ROM, and 64 Kbit RAM. As used herein, the term "real-time"
refers to outcomes occurring a substantially short period of time after a
change in the inputs affect the outcome, with the time period being a
design parameter that may be selected based on the importance of the
outcome and/or the capability of the system processing the inputs to
generate the outcome.

[0042] In embodiments of the disclosure, the parameters used for
controlling the wind turbine are calculated by the position of the blade
tips and the hub cone center in relation to the tower base. In some
embodiments, which may be combined with other embodiments disclosed
herein, further parameters such as the shaft bending and/or an azimuth
position of the nacelle are calculated from the positions of the blade
tips. In embodiments, the positions could be determined by local-area
differential GPS, radio, for example radio frequency identification
(RFID), ultrasonic or others.

[0043] Depending on the signal transmission type, the references or
reference points of, for example, two wind turbines may be taken into
account. The calculation may be performed in several ways:

[0044] For example, trilateration may be used. In this case, the duration,
or the timeofflight, of a signal transmission is taken into account, in
particular to determining the distance between the reference points and
the object, whose position may be calculated, for example the movable
portion of the wind turbine, the blade tip, the hub cone center, and/or
the top of the tower. In this case the geometry of spheres or triangles
is used. Typically, trilateration is used for GPS. In this case, the
transmitter located in the satellites 80 sends the signals to be received
by the position determination device 70 located in the movable portion.
When the signal is received by the position determination device 70, the
position determination 70 device may include only a receiver instead of
the transceiver 76. The calculation may then be performed by the position
determination device 70. In other embodiments, the signal is sent by the
position determination device 70 and is received by a receiver or
transceiver located in the tower bases. Then, the position determination
device may use a transmitter instead of a transceiver 76. The calculation
of the position or the operational parameter may be performed by a
controller located in one of the tower bases 94, by the wind turbine
controller 78, or by a controller of receivers placed at the positions of
the transmitters 96 shown in FIG. 5. When using trilateration, the signal
82, 98 may contain a time stamp. For trilateration, the wind turbine
arrangement may include a plurality of reference stations 86 connected to
the ground in addition to or instead of the tower bases.

[0045] Further, triangulation may be used. In triangulation, the location
of an object, for example the movable portion of the wind turbine, is
determined by measuring the angles to it from known reference points at
either end of a fixed baseline. The baselines between the turbines, for
example the distance between the tower bases, and at least two angles may
be measured, for example with receiver antenna diversity and phase
comparison. The base line may be, with reference to FIG. 5, the distance
100 between towers of the wind turbines. In other embodiments, the
baseline may be the distance between the transceivers of the known
reference points. For example, the distance may be determined
electronically, by sending an electromagnetic signal between the
reference points. Further, at least two angles 102 between the signals
from the known reference points may be determined. When the signal is
received by the position determination device 70, the position
determination 70 device may include only a receiver instead of the
transceiver 76. The calculation may then be performed by the position
determination device 70. In other embodiments, the signal is sent by the
position determination device 70 and is received by a receiver or
transceiver located in the tower bases. Then, the position determination
device may use a transmitter instead of a transceiver 76. The calculation
of the position or the operational parameter may be performed by a
controller located in one of the tower bases 94, by the wind turbine
controller 78, or by a controller of receivers placed at the positions of
the transmitters 96 shown in FIG. 5. For triangulation, the wind turbine
arrangement may include a plurality of reference stations 86 connected to
the ground in addition to or instead of the tower bases of other wind
turbines.

[0046] As another option, multilateration may be used. In this case, the
time difference of an arrival at three or more receivers of a signal
emitted by the object to be positioned, for example the movable portion
of the wind turbine such as the rotor blade tip, is calculated. Also, the
time difference of signals sent from at least three synchronised
transmitters to the object to be positioned, here the movable portions of
the wind turbine 10, may be used. The transmitters may be disposed in the
tower bases 94 or at the reference points 86 of a wind turbine
arrangement. Multilateration is also known as hyperbolic positioning.

[0047] Further, a combination of multilateration, triangulation, and/or
trilateration may be used, where the signal is sent by the reference
points 86 and/or by the position determination device 70.

[0048] In the case of a wind farm, it can occur that sometimes the wind
acts in a direction where some turbines are in a row. While the first
turbine would be subjected to the largest loads, the loads are reduced
for those behind. In this case the control algorithms may also use the
operational parameters to distribute the loads between the turbines. For
example, the wind turbines may communicate between each other, or to a
central control device, the state of the other wind turbines, such that a
single wind turbine is operated at the optimal working point or the wind
farm is operated at the optimal conditions.

[0049] In some embodiments, the accuracy may allow for calculating further
parameters such as tower acceleration, main shaft bending, and blade
angle.

[0050]FIG. 6 shows schematically a flow chart of a method according to an
embodiment. Typically, a wind turbine may include a movable portion that
is movable during operation of the wind turbine. In the movable portion,
a position determination device may be arranged, which includes a movable
portion transmitter and/or a movable portion receiver. In box 1000, a
signal is sent from the position determination device to the reference
points. In a further embodiment, a signal sent from the reference points
is received by the position determination. For example, the reference
points may be satellites of a global navigation satellite system or
reference points at a fixed location on the earth. The received signal,
received by either the position determination device or the reference
points, has at least one characteristic.

[0051] The characteristic of a signal may provide information about
relative position of the movable portion with respect to a reference
point, for example to determine the distance between the movable portion
and the reference point. With the characteristics of at least one signal
with respect to at least three reference points, the position of the
movable portion or the operational parameter can be determined. The
characteristic of the signal may be, for example, the round-trip time,
the time of flight, the reception time, the reception angle, which may be
used for determining the position of the movable portion or, more
precisely, the position of the movable portion transmitter or the movable
portion receiver.

[0052] In Box 1010, from the characteristic of the signal, at least one
operational parameter of the wind turbine may be determined. In
particular, for the determination of the operational parameters or the
position of the movable portion, either the at least one signal is sent
by the position determination device, then the angle, the time-of-flight,
or the time of arrival is determined at the reference points, or a signal
is sent from each reference point to the position determination device.
In further embodiments, a combination of both possibilities may be used.

[0053] The above-described systems and methods facilitate the design of a
wind turbine. More specifically, reliability is enhanced. Thus, only one
type of sender or transmitter may be used to provide several different
parameters. These senders or transmitters may send their positions to a
receiver. Depending on the transmission signal type, a controller would
calculate one or more operational parameter using either trilateration,
multilateration and/or triangulation.

[0054] The wind turbine is simplified, and the costs are reduced by
incorporating only one transmitter type and one receiver type instead of
several different sensor types. Further, effort required to maintain the
arrangement is reduced, or in some cases, removed completely. Instead of
using several different sensors, only one type of transmitter/receiver
could be used to send their position to a controller using several
different signals.

[0055] According to an embodiment, the method according to an embodiment
herein may further include determining a position of the at least one
movable portion depending on the at least one characteristic of the at
least one signal; and determining the at least one operational parameter
depending on the position of the at least one movable portion.

[0056] According to an embodiment, the method according to an embodiment
herein may further include providing or sending the at least one position
of the at least one movable portion or the operational parameter to a
control device of the wind turbine.

[0057] In some embodiments, the position is determined and sent by the
movable portion device.

[0058] For example, in an embodiment, which may be combined with other
embodiments disclosed herein, at least three of the at least three
reference points are selected from a group consisting of satellites of a
global navigation satellite system, and earth-connected reference points
being fixed to the earth.

[0059] Typically, in embodiments, at least one of the at least three
reference points is located in at least one of the wind turbine or
another wind turbine. For example all reference points may be located in
a wind turbine of a wind farm.

[0060] In an embodiment, which may be combined with other embodiments
disclosed herein, the at least one characteristic is at least one of the
following: a respective running time between the movable portion receiver
or transmitter and the at least three reference points, a round trip time
between the movable portion receiver or transmitter and the at least
three reference points, at least two signal angles between signals
between the movable portion receiver or transmitter and the at least
three reference points, and a time of arrival of the at least one signal
between the movable portion receiver or transmitter and the at least
three reference points. The characteristic may depend on the method used
for determining the operational parameter of the wind turbine or the
position of the movable portion.

[0061] In embodiments, the at least one signal for determining the at
least one characteristic is received by the movable portion receiver.
Alternatively or additionally the at least one signal is received at
receiver at at least one of the at least three reference points.

[0062] For example, in embodiments, the operational parameter is
determined by using at least one of triangulation, multilateration, or
trilateration using the at least one characteristic of the at least one
signal. The signal may be adapted to the process used for determining the
operational parameter of the wind turbine or the position of the movable
portion. For example, the signal may include a time stamp.

[0063] In embodiments, the signal is at least one of the following: an
electromagnetic signal and an ultrasonic signal. Thus, the position or
the operational parameter may be determined wireless. The frequency and
or the location of the reference points may depend to the signal type
used.

[0064] For example, in some embodiments, which may be combined with other
embodiments disclosed herein, the movable portion device is a RFID tag.
In other embodiments, also the reference points may include RFID tags.

[0065] For example, in embodiments, which may be combined with other
embodiments disclosed herein, the at least one operational parameter is
at least one of the following: a rotational speed of a wind rotor, a
rotational speed of a generator rotor, a bending of the rotor shaft, a
bending of a tower of the wind turbine, the bending of a rotor blade, an
azimuth position, and a pitch of a rotor blade.

[0066] In an embodiment, which may be combined with other embodiments
disclosed herein, the at least one movable portion is at least one of the
following:: a rotor blade tip, a portion of a rotor shaft, a portion of a
tower of the wind turbine, a portion of a nacelle of the wind turbine, a
portion of a hub of the wind turbine, and a base of the tower of the wind
turbine.

[0067] In embodiments, a method according to an embodiment disclosed
herein, may further include: operating the wind turbine depending on the
at least one operational parameter.

[0068] In embodiments, the wind turbine according to an embodiment
disclosed herein, may include at least one second controller adapted to
determine the position of the at least one movable portion depending on
at least one characteristic of the at least one signal; wherein the at
least one first controller is adapted to determine at least one
operational parameter of the wind turbine depending on the position.

[0069] For example, in embodiments, the at least one of the at least one
first controller or the at least one second controller is respectively
arranged at the movable portion.

[0070] In embodiments, the at least one first control device or the at
least one second control device are integrated in the same control unit.

[0071] Exemplary embodiments of systems and methods for controlling a wind
turbine are described above in detail. The systems and methods are not
limited to the specific embodiments described herein, but rather,
components of the systems and/or steps of the methods may be utilized
independently and separately from other components and/or steps described
herein. For example, the arrangement for determining the operational
parameters of a wind turbine are not limited to practice with only the
wind turbine systems as described herein. Rather, the exemplary
embodiment can be implemented and utilized in connection with many other
rotor blade applications.

[0072] Although specific features of various embodiments of the invention
may be shown in some drawings and not in others, this is for convenience
only. In accordance with the principles of the invention, any feature of
a drawing may be referenced and/or claimed in combination with any
feature of any other drawing.

[0073] This written description uses examples to disclose the invention,
including the best mode, and also to enable any person skilled in the art
to practice the invention, including making and using any devices or
systems and performing any incorporated methods. While various specific
embodiments have been disclosed in the foregoing, those skilled in the
art will recognize that the spirit and scope of the claims allows for
equally effective modifications. Especially, mutually non-exclusive
features of the embodiments described above may be combined with each
other. The patentable scope of the invention is defined by the claims,
and may include other examples that occur to those skilled in the art.
Such other examples are intended to be within the scope of the claims if
they have structural elements that do not differ from the literal
language of the claims, or if they include equivalent structural elements
with insubstantial differences from the literal language of the claims.